During operation of a piezoelectric pump, a driving system provides electric energy to drive a piezoelectric actuator of the piezoelectric pump. Consequently, the piezoelectric actuator performs a cyclic action to drive the operation of the piezoelectric pump.
Conventionally, there are three kinds of driving systems for driving the piezoelectric pump. The first driving system provides a fixed output voltage and controls a fixed working frequency of the piezoelectric actuator; the second driving system provides a variable output voltage and controls a fixed working frequency of the piezoelectric actuator; and the third driving system provides a fixed output voltage and controls a variable working frequency of the piezoelectric actuator.
However, the above-mentioned driving systems have drawbacks respectively. Regarding the first driving system, each piezoelectric pump actually has different characteristic due to different design of structure, size, thickness of the piezoelectric plate, or assembling tolerance. As a result, when being applied to the fixed output voltage and being operated at the fixed frequency, piezoelectric pumps would output different gas pressure. Thus, the first driving system causes difficulty in precisely control the performance and the output flowrate of different piezoelectric pumps.
Regarding the second driving system, the problem is poor compatibility. As mentioned, the structure design and the thickness of the piezoelectric plate affect physical characteristics of piezoelectric pumps, so each type of piezoelectric pumps has an optimal working frequency. However, the second driving system fails to operate the different types of piezoelectric pumps at their optimal working frequencies. For instance, the optimal working frequencies of three different kinds of piezoelectric pumps are 100 kHz, 105 kHz, and 95 kHz respectively. The second driving system controls the piezoelectric actuators of these three kinds of piezoelectric pumps to work at a fixed working frequency, which is approximately average of their optimal working frequencies, e.g., 100 kHz. Under this circumstance, a higher voltage or a lower voltage is required to drive the piezoelectric pumps that have the optimal working frequencies of 105 kHz and 95 kHz. However, if the output voltage is too high, the piezoelectric property of the piezoelectric actuator may be lost and thus the piezoelectric pump is damaged.
Regarding the third driving system, it results in the abrupt increase or decrease of the performance of the piezoelectric pump and narrows the range of the controllable working frequency of the piezoelectric pump. Thus, applicability of the third driving system is quite limited.
Therefore, there is a need of providing an improved driving system for a piezoelectric pump in order to overcome the above drawbacks.